A laser radar device, as it is known, emits laser light into the air and receives scattered light reflected by fine liquid or solid particles (aerosols) floating in the air, to calculate a wind speed. A possible use of this laser radar device is mounting on an unsteadily moving platform such as an airplane or a floating body on the ocean. Usually, such a platform unsteadily moves due to an external factor such as a wind or a wave.
For example, a conventional laser radar device mounted in a platform is disclosed by Patent Literature 1. The conventional laser radar device performs a Fourier transform on scattered light scattered by aerosols in the air for each time, thereby to calculate frequency spectra of the scattered light for respective times. After that, an integration of the frequency spectra for respective times is performed, and the value of a wind speed in a line-of-sight direction is calculated from the peak value of a frequency spectrum resulting from the integration. For the value of the wind speed calculated from the frequency spectrum resulting from the integration, the motion amount is compensated for, and thereby a value of the wind speed in which the influence of the motion is filtered out is obtained. In this way, the conventional laser radar device performs compensation for the motion. The motion amount for use in the compensation is the average of motion amounts over a period of time during which the integration is performed.